MEMS Diaphragm Support Loop Segmentation for Counter Electrode Reliability
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Solution Overview
Problem
Existing MEMS microphones with a double-membrane structure face challenges in reducing self-noise and maintaining reliability due to the need for closely spaced small circular pillars, which complicates acoustic damping and capacitance design.
Innovation Solution
The use of support loop members with alternating first and second sections and notches, connected to both membranes, reduces the need for slots in the counter electrode, increasing the distance between support elements and improving the stiffness of the counter electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If small circular pillars are used to connect the two membranes, then the structure is prevented from collapsing, but the pillars need to be closely spaced (5-20 um) to prevent excessive membrane deformation, which reduces counter electrode reliability and limits acoustic damping and capacitance design
Solution Approach 1:
The support structure is segmented from small circular pillars to loop members with multiple sections. Each loop member contains multiple first sections and second sections arranged concentrically, creating a modular support system that reduces the number of individual support elements needed while maintaining structural integrity and preventing membrane collapse.
Solution Approach 2:
The support structure transitions from one-dimensional small circular pillars to two-dimensional loop members with concentric sections. This dimensional change allows the support function to be distributed across a larger area, reducing the need for closely spaced individual supports and improving counter electrode reliability.
2Stability of the object's composition
If small circular pillars are closely spaced to prevent membrane deformation, then membrane stability is improved, but the number of slots required in the counter electrode increases, reducing acoustic damping performance
Solution Approach 1:
The loop members are divided into multiple first sections and second sections arranged concentrically, creating a segmented support structure. This segmentation allows the support function to be distributed more efficiently, maintaining membrane stability while reducing the total number of support elements and corresponding slots in the counter electrode.
Solution Approach 2:
Different sections of the loop members (first sections and second sections) are positioned at different radial locations to provide localized support where needed. This allows membrane stability to be maintained in critical areas while reducing support density in other areas, preserving acoustic damping performance.
3Strength
If small circular pillars are used to support the membranes, then structural integrity is maintained, but design limits are imposed on acoustic damping and capacitance of the microphone
Solution Approach 1:
The support structure evolves from one-dimensional pillars to two-dimensional loop members with concentric sections. This dimensional expansion provides greater design flexibility, allowing the support function to be decoupled from acoustic damping and capacitance design constraints.
Solution Approach 2:
The loop members are segmented into multiple first and second sections that can be independently positioned and sized. This segmentation allows optimization of each section's location and dimensions to simultaneously maintain structural integrity and achieve desired acoustic damping and capacitance characteristics.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design enhances the reliability and stability of the microphone by reducing the number of slots required in the counter electrode, improving acoustic damping and capacitance, while maintaining the structural integrity of the membranes under varying pressures.
Implementation Method 1
If the pressure in the accommodating space is reduced, this structure will significantly reduce the self-noise... The plurality of support loop members arranged concentrically in the accommodating space. Opposite ends of each of the plurality of support loop members along a vibration direction are respectively connected to the first membrane and the second membrane.
Implementation Method 2
Each of the plurality of support loop members is composed of a plurality of first sections concentrically arranged, the plurality of first sections are arranged as a loop member at intervals. A first notch is formed between two adjacent first sections... the plurality of support loop members are arranged at intervals along a radial direction of the diaphragm
Data Source
AI summary
Provided is an MEMS device, including: a substrate having back cavity passing thererthrough; a diaphragm connected to the substrate and covers the back cavity, the diaphragm includes first and second membranes, and accommodating space formed therebetween; a counter electrode; and support loop members arranged concentrically. Opposite ends of the support loop member are connected to the first and second membranes. The support loop members are arranged at intervals. Each support loop member has first sections concentrically arranged as a loop member at intervals. A first notch is formed between two adjacent first sections. In at least one support loop member, the first section has second sections concentrically arranged as a loop member at intervals. A second notch is formed between two adjacent second sections. By a larger first section, distance between adjacent first sections is larger, the technical problem that large number of slots required for counter electrode is solved.